Electrode structure and method for electronic tubes



z- 5 w. c. JOHNSON ETAL 2,849,638

ELECTRODE STRUCTURE AND METHOD FOR ELECTRONIC TUBES 4 Sheets-Sheet 1 Filed Feb. 25, 1955 2nd Anode Conveyor ond Injector y ee V on n o 0 CI n r m w, m x C On ho r we m Mn m C Is? Grid Assembly Conveyor ond Injector Conveyor ond Injector 2nd Grid Assembly Conveyor and Injector F 3- INVE NTORS Warren 0. Johnson a Richard W. Anderson. k M ATTORNEY WITNESSES W Mada/4% ELECTRODE STRUCTURE AND METHOD FOR ELECTRONIC TUBES Filed Feb. 25, 1955 Aug. 26, 1958 w. c. JOHNSON ETAL 4 Sheets-Sheet 2 Aug. 26, 1958 w. c. JOHNSON ETAL 2,849,638

ELECTRODE STRUCTURE AND METHOD FOR ELECTRONIC TUBES Filed Feb. 25, '1955 4 Sheets-Sheet 3 1953 w. c. JOHNSON ETAL 2,849,538

ELECTRODE STRUCTURE AND METHOD FOR ELECTRONIC TUBES Filed Feb. 25, 1955 4 Sheets-Sheet 4 ELECTRODE STRUCTURE AND METHOD FOR ELECTRONIC TUBES Warren C. Johnson, Elmira, and Richard W. Anderson, Horseheads, N. Y., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application February 25, 1955, Serial No. 490,452 12 Claims. (Cl. 313-457) Our invention relates to manufacturing machines and l in particular relates to automatic machines for manufacturing electron tubes of improved design as described herein and which can be used in the same manner as those electron tubes of types widely employed in the radio art.

At the present day, it is the usual practice in manufacturing radio tubes to fabricate separate parts, such as plates, grids, cathodes on separate machines, then to clean or otherwise treat them, and then to assemble these parts into the complete tube structure largely by hand methods. Because of high labor costs, however, some way of performing the assembly by automatic machinery is greatly desired.

It is accordingly an object of our invention to provide a process and apparatus for forming the electrodes of electron tubes such as. the types commonly used in radio or the like and assembling them on supporting stems by automatic machinery.

It is another object of our invention to provide novel arrangements for fixing precisely the interelectrode and other critical dimensions of electron structures for such tubes.

It is also an object to provide an electrode structure for such tubes which employ insulating plates mechanically supporting various parts and which is arranged to accurately fix the electrode spacings notwithstanding variances in thickness of said insulation.

The foregoing and other objects of our invention will become apparent to those skilled in the art upon reading the following description taken in connection with the drawings in which:

Figure 1 is a schematic view in perspective, partly in section, showing a double triode to the fabrication of which our invention may be applied;

Fig. 2 is an exploded view in perspective showing how the electrodes of Fig. l or a similar tube are formed and assembled;

Fig. 3 is a layout diagram of the above-mentioned automatic assembling machine showing the various stations of the turret-head for assembling a double triode;

Fig. 4 is a sectional view showing a subassembly of screen grid and control grid for a beam-type pentode;

Fig. 5 is an exploded view of the grid subassembly of Fig. 4; and

Fig. 6 is an exploded view of a subassembly of anode and beam electrode to be combined with the Fig. 4 subassembly in fabricating such a pentode.

Referring in detail to Fig. 1 and Fig. 2, a double triode formed in accordance with our invention comprises a flat support-plate 1 having a stilfening bar 2 at one end, and a pair of anodes 3, grids 4 and cathodes 5 on its opposite sides. Theplate 1 has an oblong central opening in which the cathode heater (not shown) is positioned, its in-leads being connected to two metallic bars 7 and 8 which act as stifieners for the other end of support-platel. Thexexact form of support-plate 1 and United States Patent 0 ice 2,849,638 Patented Aug. 26 1958 view of Fig. 2. Support-plate 1 may be stamped out of mica or made from ceramic or any other suitable insulating material, and have its stiffening bars 2, 7 and 8 attached before being fed to our assembling machine if they are required.

Referring to Fig. 2, the cathode shell comprises two metallic channel-shaped members 5, coated with emissive oxides on their outside surface and having on each side two projecting legs 11 bent over and pointed at the ends. The members 5 may be stamped out of metal and coated with oxides before assembling with supportplate 1 as is described below. The oxide coatings might also be applied after the members have been attached to the support-plate 1.

In the electrode forming and assembling machine employing our invention, the support-plate 1 described above is fed from a hopper to a holder on a turret-head which turns about a vertical axis at successive intervals from one station to another where the various electrodes are installed one after another. The channel member 5 starts at station 1 with its oxide coated face down on the holder and one support-plate 1 is dropped onto the pointed tips of its legs 11. Holes 12 are provided in support-plate 1 through which the pointed tips of legs 11 pass. Suitable plungers (not shown) cramp the tips of legs 1.1 over against the mica, holding channel member 5 firmly in place thereon with its emissive-oxide surface at a precisely determined distance below the lower face of mica support-plate 1.

The turret is then rotated to bring the support-plate 1 and attached cathode 5 to station 2 where the second cathode 5 is inserted into the top of plate 1 with its legs 11 in the appropriate holes 12. Suitable plungers (not shown) are again used to bend the tips of legs 11 over against the mica.

After this operation the turret then rotates to bring the support-plate 1 With both cathode sections 5 attached to station #3 Where the grids 4 are to be attached.

The grid 4 comprises a frame 13 of punched sheet metal, to which cross-wires 14 are fastened by any means well known in the arts; and also a grid-support 15 which is more fully described below. The grid-frame 13 and cross-wires 14 may be fabricated separately, fastened to support 15, and fed from a hopper to the automatic assembling machine. It would, of course, be no diflicult matter to employ automatic machinery for making the grid-frames 13 and supports 15 and for assembling them together and injecting them directly into the turret of the assembly machine at position #3 from the prefabricating component of the machine. Also, it can readily be understood that in certain instances frame 13 might be dispensed with and Wires 14 fastened directly to support-frame 15.

The grid-supports 15 may be formed in a progressive die constituting an integral part of a prefabrication section ofthe machine. This die first stamps the proper shape to be bent up into grid-support15 out of fiat strip material, and then feeds it through bending stages which bend the three legs 16 at right angles to the rectangular frame-portion and turns out the ledges 17 at the right discathode surfaces regardless of the thickness of the support-member 1.

When the turret rotatesthe support-plate 1 with the attached cathode sections 5 to position 3, a grid assembly 4 made as just described is automatically dispensed into the turret in such a way that the pointed tips of legs 16 pass through the properly situated openings 18 in the mica 1. The ledges 17 are pressed against the face of support-plate 1 and the tips of legs 16 are then bent against the face of the support-plate 1 by plungers which are not shown.

At station #4 the second grid assembly 4 is attached to support-plate 1 in a manner similar to that just described, but to the opposite side of the support-plate 1 from that to which the first grid 4 was attached.

At station #5 an anode 3 is inserted and fastened to the support-plate 1 and at station #6 the second anode 3 is attached to the opposite side of support-plate 1.

The anodes (shown at 3 in Fig. 2) are formed on a separate prefabricating machine where a properly cleaned strip of sheet metal is fed through a progressive punch press which stamps a blank of proper outline and bends it up to form the anode. Thus, the anodes 3 each have support-legs having ledges 21 at a proper distance from the top plane to properly space the active anode-face 22 from the grid-wires 14 when ledges 21 bear against the surface of the support-plate 1. Also there is provided the pointed tips on legs 19 which are to be inserted in openings in the support-plate 1 and then bent over against the face of support-plate 1 while ledges 21 are held tightly against the opposite face.

The structure assembled by the procedure so far described would constitute the electrode system (except cathode-heater) of a double triode. This might be supported on inleads of a suitable stem by welding the anode, grid and cathode to such inleads, for example, inserting the cathode heater inside the channel-members 9 by hand, for instance. The stem could then be inserted in a lamp bulb and exhausted by conventional methods forming no part of our present invention.

When it is desired to form a single triode, the above described procedure would be varied by connecting the corresponding elements on the opposite faces of supportplate 1 together at the time of connecting the elements to the inleads. An alternate method would be to adjust the machine to skip operations at alternate stations so that only one set of elements would be attached to only one face of support-plate 1. It should be noted that each of the elements is designed so that its support-legs are olfset with respect to each other on opposite sides. It is evident that with this structure the leg-tips of equivalent elements on opposite sides of support-element 1 will pass through the latter at different points and can be clamped against plate 1 without interfering with each other. This feature provides both operating clearance for the clamping plungers and electrical isolation between elements on opposite faces of plate 1.

To further illustrate the principles of our invention, we will describe their application to a tube of more complex electrode structure, i. e., a beam pentode of the 6CB6 type.

The cathode described above and the machine and method for assembling it may be used for the 6CB6 pentode so the description of its fabrication and assembling with the support-plate 1 at stations one and two of Fig. 3 will not be repeated.

The above tube has, in addition to an anode and cathode, a beam electrode next to the anode, then a screen grid and next to the cathode a control grid. The two grids are shown in section in Fig. 4 and are mounted on a mica support 51', shown in more detail in Fig. 5, which may be formed elsewhere and fed from hopper at a station of a prefabricating turret-head. The screen grid 52 in Fig. 5 will usually be fabricated elsewhere and supplied from a hopper at the station, although of course, a progressive punch press for forming its rectangular frame with four dependent legs, and a welding machine for applying its cross-wires 54 in ways well-known in the art might, if desired, be supported on the assembling 5. machine frame at the station. The screen grid 52 may be accurately spaced away from the top surface of mica support 51 by dimples 55 formed in the sheet metal when it is stamped out.

At the station the screen grid 52 is held with its legs 53 pointing upward and the mica support 51 deposited on it with the legs 53 of the latter protruding through properly positioned openings and the dimples 55 spacing the grid wires 54 a predetermined distance from the lower face of mica support 51. The turret then turns to a new station of the prefabricating unit.

At this new station the control grid 57 is either fed from a hopper after fabrication elsewhere or may obviously be fabricated by a progressive punch-using die from sheet stock, and a welding apparatus mounted on the assembling machine at that station. It is formed with downturned ends each provided with two downwardly extending pointing legs 59 and with ledges 60 which bear on and space its grid wires 61 by a predetermined distance from the upper face of mica support 51. Control grid 57 is likewise provided with four upwardly extending side wall portions 62 having spacer-ledges 63 and pointed legs 64 for a purpose described below. Control grid 57 is deposited on the holder at the station with its legs 59 pointing upward and mica support 51 with grid 52 already attached is deposited on it so that the pointed tips of legs 59 pass through properly located openings 65 in support 51. Ledges 60 may be bent, when pressed up, through a little less than ninety degrees; and when the support 51 is pressed down against them, they are able to give slightly until grid-wires 54 are spaced at just the desired distance (fixed by a conventional jig) from the surface of mica support 51 and grid-wires 61 or, of course, ledges 60 could have been preformed to give just the right spacing. The protruding ends of legs 59 are then bent over and clamped against the under surface of support 51, thus completing a subassembly of control grid and screen grid aflixed to mica support 51.

Fig. 6 shows the components of the beam-electrode and anode assembly which comprises a mica support 71, the beam-electrode 72 and the anode 73. The anode 73 is formed at a station of the turret-head by a progressive punch and die press from a roll of properly cleaned sheet metal; or it may be made elsewhere and fed from a hopper. It is in the form of a trough having four legs with pointed tips extending upward from its sidewalls, and also having ledges 75 bent over through an angle of slightly less than ninety degrees from the sidewalls. The anode may also be provided with a tab 76 to which an anode-lead may be connected.

The anode 73 is deposited on the holder at the station with its legs 74 pointed upward and the mica support 71 is deposited so that the legs 74 protrude through opening 77 and adjacent to lips A. A pressing plate then presses mica support 71 down, bending the ledges 75 just enough to produce a desired spacing between the back face of anode 73 and the upper face of support 71. The projecting legs 74 are then bet over and cramped against the upper face of mica support 71.

At the next station of the turret beam plate 72 is inserted, having been made by a suitable punch and die from sheet stock. The beam electrode has a rectangular window 81 and has sidewalls 82 having projecting ears 83 and ledges 84 on its lower face. It also has sidewalls 85 provided with ears 86 and ledges 87 extending upwardly from its main plane. The beam-electrode 72 may be deposited on mica support 71 at the station with its cars 83 projecting downward through properly located openings in the latter; be pressed downward against the tension of ledges 84 until its upper face is spaced by the desired distance from the upper face of mica support 71; and the ears 83 be then cramped against the lower face of the mica. The positions of the anode face and the window 81 thus are items definitely and precisely fixed relative to thenpper face of mica support 71, however thick or thin the latter may be. A subassembly of anode and. beam electrode aflixed to mica support 71 has thus been produced at this station of the turret. The two subassemblies just described are then fed into a station of the turret of the main assembly machine.

The anode subassembly is held with its ears 86 pointing upward and the mica support 51 carrying the grid subassembly from station four is set down on it so that ears 86 project through properly positioned openings 88 in support 51, Fig. 5, and is pressed down against the tension of ledges 87 until the upper face of mica support 51 is at the desired distance above the back face of anode 73. The tips of ears 86 are then bent over and cramped against the face of mica support 51, thus locking the anode and grid subassemblies together with precisely determined spacings of anode, beam electrode, screen grid and control grid from the upper face of mica support 51.

At another station of the main assembly turret, the above described assembly is positioned with ears 64 of the control grid pointing upward, and the support-plate 1, with cathode 5 attached, similar to that used for the triode, is set down so that the cars 64 protrude through four properly positioned openings in cathode supportplate 1. The latter is then pressed down against the reaction of ledges 63 which bear against its lower face until the oxide coated surface of the cathode is spaced the desired distance from the upper face of mica support 51 (and hence spaced by fixed predetermined distances from both grids, beam electrode window, and anode) whereupon the ends of legs 64 are bent over and cramped against the face of support-plate 1.

At this station the electrode assembly for a single-sided pentode has thus been completed. Where a double-sided pentode is desired, a subassembly of anode, beam electrode and grids just like that produced at the station above is positioned, anode downward, on the holder at another turret station and another single sides electrode assembly completed at another station is set down on it and the two assemblies fastened together by any suitable method.

We claim as our invention:

1. An electrode structure for an electrical discharge tube comprising a support plate of insulating material having a planar portion including a central window, a cathode of sheet metal having an electron-emitting surface directly supported from said support-plate parallel to the plane of said window and said planar portion, said electron-emitting surface being above the plane of said window, a grid-electrode formed from sheet metal and having a central opening crossed by wire members parallel to said electron-emitting surface, said grid-electrode having side-portions substantially perpendicular to and directly aflixing it to said support-plate so that said grid electrode is in parallel spaced relation to said electron-emitting surface, and an anode formed from sheet metal having side-members substantially perpendicular to and directly supporting it from said support-plate so that said anode is in parallel spaced relation to said electronemitting surface.

2. The method of fabricating an electrode structure for electrical discharge tubes which comprises the steps of forming a support-plate of sheet insulating material with a central window surrounded by smaller openings, fastening a sheet-metal cathode to said support-plate parallel to said window by cramping projections of said metal through certain of said smaller openings against the reverse side of said support-plate; stamping and pressing a grid-frame into channel form from sheet-metal and fastening it to said support-plate by cramping projections of the last-mentioned sheet-metal through certain others of said smaller openings against the reverse side of said support-plate.

3. An electrode structure for an electrical discharge tube which comprises a support-plate of insulating material and a plurality of electrodes each comprising a planar portion and supports spacing it from said supportplate, said planar'portion of each of said electrodes being substantially parallel to said support plate, said supports being substantially perpendicular to said support-plate, said supports having ledges intermediate their length adapted to bear against one face of said support-plate and end-portions projecting through openings in said plate and bent over and cramped against the other face of said support-plate.

4. An electrode structure for an electrical discharge tube comprising a support-plate of insulating material having a planar portion including a central window, a cathode of sheet metal having an electron-emitting surface directly supported from said support-plate parallel to the plane of said window and said planar portion, said electron-emitting surface being above the plane of said window, a grid-electrode formed from sheet metal and having a central opening crossed by wire members parallel to said electron-emitting surface, said grid-electrode having side-portions substantially perpendicular to and directly afi'ixing it to said support-plate so that said grid electrode is in parallel spaced relation to said electron-emitting surface, and an anode formed from sheet metal having side-members substantially perpendicular to and directly supporting it from said support-plate so that said anode is in parallel spaced relation to said electron-emitting surface, said support plate insulating material being mica.

5. An electrode structure for an electrical discharge tube comprising a support-plate of insulating material having a planar portion including a central window, a cathode of sheet metal having an electron-emitting surface directly supported from said support-plate parallel to the plane of said window and said planar portion, said electron-emitting surface being above the plane of said window, a grid-electrode formed from sheet metal and having'a central opening crossed by wire members parallel to said electron-emitting surface, said grid-electrode having side-portions substantially perpendicular to and directly aifixing it to said support-plate so that said grid electrode is in parallel spaced relation to said electron-emitting surface, and an anode formed from sheet metal having side-members substantially perpendicular to and directly supporting it from said support-plate so that said anode is in parallel spaced relation to said electron-emitting surface, said anode and said grid electrode being attached to said support plate by portions of said sheet metal extending through openings in said support plate and bent over and cramped against it.

6. An electrode structure for an electrical discharge tube comprising a support-plate of insulating material having a planar'portion incluuding a central window, a cathode of sheet metal having an electron-emitting surface directly supported from said support-plate parallel to the plane of said window and said planar portion, said electron-emitting surface being above the plane of said window, a first grid-electrode formed from sheet metal and having a central opening crossed by wire members parallel to said electron-emitting surface, said first gridelectrode having side-portions substantially perpendicular to and directly affixing it to said support-plate so that said grid electrode is in parallel spaced relation to said electron-emitting surface, and'a first anode formed from sheet metal having side-members substantially perpendicular to and directly supporting it from said supportplate so that said first anode is in parallel spaced relation to said electron-emitting surface, said first anode and said first grid electrode being attached to said support plate by portions of said sheet metal extending through openings in said support plate and bent over and cramped against it, a second anode and a second grid electrode, said second anode and said grid electrode being supported in a similar way to that of said first anode and said first grid electrode on the reverse side of said support plate.

7. An electrode structure for an electrical discharge tube comprising a support-plate of insulating material having a planar portion including a central window, a cathode of sheet metal having an electron-emitting surface directly supported from said support-plate parallel to the plane of said window and said planar portion, said electron-emitting surface being above the plane of said window, a grid-electrode formed from sheet metal and having a central opening crossed by wire members parallel to said electron-emitting surface, said grid-electrode having side-portions substantially perpendicular to and directly aflixing it to said support-plate so that said grid electrode is in parall l spaced relation to said electronemitting surface, and an anode formed from sheet metal having side-members substantially perpendicular to and directly supporting it from said support-plate so that said anode is in parallel spaced relation to said electron-emitting surface, said anode and said grid electrode being attached to said support plate by portions of said sheet metal extending through openings in said support plate and bent over and cramped against it, said portions of said sheet metal which are on opposite sides of said central Window being dissymmetrical relative to any axis passing through the center of said window in the plane thereof.

8. The method of fabricating an electrode structure for electrical discharge tubes which comprises the steps of forming a support-plate of sheet insulating material with a central window surrounded by smaller openings, fastening a sheet-metal cathode to said support-plate parallel to said window by cramping projections of said metal through certain of said smaller openings against the reverse side of said support-plate; stamping and pressing a grid-frame into channel form from sheet-metal and fastening it to said support-plate by cramping projections of the last-mentioned sheet-metal through certain others of said smaller openings against the reverse side of said support-plate; stamping and pressing an anode into a modified channel-form from sheet-metal and fastening said anode to said support plate by cramping projections of said last-mentioned sheet metal through still others of said smaller openings against said reverse side of said supporting plate.

9. An electrode structure for an electrical discharge tube comprising a support-plate of insulating material having a planar portion including a central window, a cathode of sheet metal having an electron-emitting surface directly supported from said support-plate parallel to the plane of said window and said planar portion, said electron-emitting surface being above the plane of said window, a grid-electrode formed from sheet metal and having a central opening crossed by Wire members parallel to said electron-emitting surface, said grid-electrode having side-portions substantially perpendicular to and directly affixing it to said support-plate so that said grid electrode is in parallel spaced relation to said electronemitting surface, and an anode formed from sheet metal having side-members substantially perpendicular to and directly supporting it from said support-plate so that said anode is in parallel spaced relation to said electronemitting surface, said support plate insulating material being a ceramic.

10. An electrode structure for an electrical discharge tube which comprises a support-plate of insulating material and a plurality of electrodes each comprising a cs planar portion and supports spacing it from said supportplate, said planar portion of each of said electrodes being substantially parallel to said support plate, said supports being substantially perpendicular to said support-plate, said supports having ledges intermediate their length adapted to bear against one face of said support-plate and end-portions projecting through openings in said plate and bent over and cramped against the other face of said support-plate, said ledges flexing to exert resilient pressure against said one face.

11. An electrode structure for an electrical discharge tube which comprises a support-plate of insulating material and a plurality of electrodes each comprising a planar portion and supports spacing it from said supportplate, said planar portion of each of said electrodes being substantially parallel to said support plate, said supports being substantially perpendicular to said supportplate, said supports having ledges intermediate their length adapted to bear against one face of said supportplate and end-portions projecting through openings in said plate and bent over and cramped against the other face of said support-plate, certain of said electrodes comprising sheet-metal channels, the sides of which comprise said supports and said ledges being portions of said sides which are bent over through an angle of less than 12. An electrode structure for an electrical discharge tube comprising a support-plate of insulating material having a planar portion including a central window, a cathode of sheet metal having an electron-emitting surface directly supported from said support-plate parallel to the plane of said window and said planar portion, said electron-emitting surface being above the plane of said window, a grid-electrode formed from sheet metal and having a central opening crossed by wire members parallel to said electron-emitting surface. said grid-electrode having side-portions substantially perpendicular to and directly affixing it to said support-plate so that said grid electrode is in parallel spaced relation to said electron-emitting surface, and an anode formed from sheet metal having side-members substantially perpendicular to and directly supporting it from said support-plate so that said anode is in parallel spaced relation to said electron-emitting surface, said anode and said grid electrode being attached to said support plate by portions of said sheet metal extending through openings in said support plate and bent over and cramped against it, said portions of said sheet-metal having bent out ledges in resilient engagement with one face of said support plate.

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